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assigned value will possible override itself [message #522244]

Sun, 21 March 2010 17:27

John J. Franey

Messages: 55
Registered: July 2009

Member

I understand why I get this warning:

Quote:

The assigned value of feature 'end' will possibly override itself because it is used inside of a loop.

In my dsl grammar, I want to say that 'end' and 'start' can appear in any order. That's all I want to say. I'll accept that the values can be overwritten. My question: is there a way to avoid the loop or the warning message but still permit these to appear in any order?

Entity:
  (
     ('end' end=INT) |
     ('start' start=INT)
  )*

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Re: assigned value will possible override itself [message #522246 is a reply to message #522244]

Sun, 21 March 2010 17:34

Henrik Lindberg

Messages: 2509
Registered: July 2009

Senior Member

If you only have two rules, you could always do this:

Entity:
(
(('end' end=INT) ('start' start=INT)?)
|(('start' start=INT) ('end' end=INT)?)
)

- henrik

On 3/21/10 6:27 PM, John J. Franey wrote:
> I understand why I get this warning:
>
> Quote:
>> The assigned value of feature 'end' will possibly override itself
>> because it is used inside of a loop.
>
>
> In my dsl grammar, I want to say that 'end' and 'start' can appear in
> any order. That's all I want to say. I'll accept that the values can be
> overwritten. My question: is there a way to avoid the loop or the
> warning message but still permit these to appear in any order?
>
>
> Entity:
> (
> ('end' end=INT) |
> ('start' start=INT)
> )*
>
>

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Re: assigned value will possible override itself [message #522268 is a reply to message #522246]

Sun, 21 March 2010 23:29

John J. Franey

Messages: 55
Registered: July 2009

Member

Henrik Lindberg wrote on Sun, 21 March 2010 13:34

If you only have two rules, you could always do this:

Entity:
(
(('end' end=INT) ('start' start=INT)?)
|(('start' start=INT) ('end' end=INT)?)
)

- henrik

Terrific idea. Thanks.

However, I do indeed have much more than two rules.

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Re: assigned value will possible override itself [message #522269 is a reply to message #522268]

Sun, 21 March 2010 23:39

Sebastian Zarnekow

Messages: 3118
Registered: July 2009

Senior Member

Hi John,

Xtext 1.0 will have the concept of unordered groups (in fact, the
feature is already available in the latest milestone but has still some
problems in the content assist scenario). Unordere groups allow to
define a set of alternatives that may occur in arbitrary order but each
one only onces.

It looks like this:

Entity:
('start' start = INT)?
& ('end' end = INT)?
;

Regards,
Sebastian
--
Need professional support for Eclipse Modeling?
Go visit: http://xtext.itemis.com

Am 22.03.10 00:29, schrieb John J. Franey:
> Henrik Lindberg wrote on Sun, 21 March 2010 13:34
>> If you only have two rules, you could always do this:
>>
>> Entity:
>> (
>> (('end' end=INT) ('start' start=INT)?)
>> |(('start' start=INT) ('end' end=INT)?)
>> )
>>
>> - henrik
>
>
> Terrific idea. Thanks.
>
> However, I do indeed have much more than two rules.
>
>

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Re: assigned value will possible override itself [message #522339 is a reply to message #522269]

Mon, 22 March 2010 12:43

John J. Franey

Messages: 55
Registered: July 2009

Member

Thanks.

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Re: assigned value will possible override itself [message #1694014 is a reply to message #522339]

Thu, 30 April 2015 06:47

Markus Duft

Messages: 35
Registered: March 2015

Member

Hey. Sorry for resurrecting this stone old post - but my problem seems pretty related Smile

I have something like this:

Persistent:
	(modifiers=PersistentModifier) 'persistent' name = FQName 
	 inheritance=PersistentInheritance?
		'{'
			('data-category' category=PersistentCategory ';')? 
			(properties+=Property|elements+=StructuralElement)*
		'}'
;

this allows for properties and elements to appear intermixed in any order, which is cool Smile

however, data-category must be before any of these elements appear. So this is possible:

persistent XX {
    data-category Protocol;
    property label "something";
    attribute something : String;
    property something "something";
}

but i would like to somehow achieve this:

persistent XX {
    property label "something";
    attribute something : String;
    data-category Protocol;
    property something "something";
}

If I add the data-category rule to the (|)* group I will get the warning that data-category might override itself (if it appears multiple times). How could I make sure that it can only appear once, but still be intermixed somewhere in the code? Is it possible?

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Re: assigned value will possible override itself [message #1694017 is a reply to message #1694014]

Thu, 30 April 2015 07:01

Christian Dietrich

Messages: 14665
Registered: July 2009

Senior Member

Hi,

the feature "any order" is called unordered group and can be found in the docs

Twitter : @chrdietrich
Blog : https://www.dietrich-it.de

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Re: assigned value will possible override itself [message #1694032 is a reply to message #1694017]

Thu, 30 April 2015 07:59

Markus Duft

Messages: 35
Registered: March 2015

Member

Hey,

I know about unordered groups, but i cannot imagine how to create what i described with unordered groups....?! Can you given an example? I want 3 different objects in arbitrary order, but two of them are collections, and one is not.

Thanks!

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Re: assigned value will possible override itself [message #1694041 is a reply to message #1694032]

Thu, 30 April 2015 08:43

Christian Dietrich

Messages: 14665
Registered: July 2009

Senior Member

Model:
	(a+=A|
	b+=B)*
	& (c=C)?
	& (a+=A|
	b+=B)*
	;

Twitter : @chrdietrich
Blog : https://www.dietrich-it.de

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Re: assigned value will possible override itself [message #1694047 is a reply to message #1694017]

Thu, 30 April 2015 09:03

Sebastian Zarnekow

Messages: 3118
Registered: July 2009

Senior Member

On 30.04.15 09:01, Christian Dietrich wrote:
> Hi,
>
> the feature "any order" is called unordered group and can be found in
> the docs

It's not even necessary to use unordered groups here. You may want to
try this pattern:

Persistent:
(modifiers=PersistentModifier) 'persistent' name = FQName
inheritance=PersistentInheritance?

'{'
(prop+=Prop|ele+=Ele)*
('d-c' cat=Cat ';' (prop+=Prop|ele+=Ele)*)?
'}'
;

Best,
Sebastian
--
Looking for professional support for Xtext, Xtend or Eclipse Modeling?
Find help at http://xtext.itemis.com or xtext(@)itemis.com
Blog: zarnekow.blogspot.com
Twitter: @szarnekow
Google+: https://www.google.com/+SebastianZarnekow

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